Solar Cells With Environmentally Friendly Aluminum Slurry Performance Study

Aluminum pastes used in solar cells have already been industrialized with high production and low price. But the study on the stability of aluminum pastes is lagging behind. Usually, aluminum pastes need to be applied within four hours, otherwise sedimentation and agglomeration will occur. During the firing process, defects like aluminum beads are almost inevitable as industrial aluminum pastes are not stable. Additionally, one important composition of aluminum paste is glass frit whose basis is poisonous element Pb. As environment protection become more and more important, displacement of Pb is indispensable. In order to solve these problems, a environmentally friendly aluminum paste with good volatility and stability was prepared in this paper. The thickness of BSF was10μm and sheet resistance was8mΩ.The volatility of different solvent was measured by TG. The mixture of three solvent proved to be the best. The interaction between ethyl cellulose and three different surfactants were measured by viscometer and surface tensiometer. The results revealed that with the increasing of SDBS and lecithin, the viscosity of organic vehicle would increase at first and then decrease. While the surface tension showed a downward trend with two turning points. In the solution of SDBS and ethyl cellulose(8wt%), the CAC of SDBS was3wt%and CMC was about13wt%. In the solution of lecithin and ethyl cellulose(8wt%), the CAC of lecithin was1wt%and CMC was about4wt%. The stability of aluminum pastes were measured by fineness dispersion meter, sedimentation and rheometer. The results indicated that the best amount of SDBS was7wt%, lecithin was1.7wt%, span85was0.8wt%and ethyl cellulose was8wt%.16hours ball milling was appropriate.The glass formation zone of a quaternary system was discussed. The structure and properties of glass were characterized by FTIR, XRD, DSC. A glass of423℃transition temperature was prepared. The effects of firing peak temperature and glass content on the morphology and sheet resistance of BSF were tested. The best firing peak temperature was800℃and glass content was4wt%.